1. Field of the Invention
The present invention relates generally to livestock handling equipment, and more particularly to a livestock identification apparatus for automatically identifying and sorting livestock as they walk through the apparatus.
2. Discussion of the Prior Art
Livestock identification apparatuses for automatically identifying and sorting livestock are known in the art. For example, U.S. Pat. No. 4,798,175 discloses an electronic identification system for sensing the presence of livestock passing through an alley and for providing an electrical signal when an animal to be sorted is present. The identification system includes a double loop antenna supported on a flexible curtain that generates a multidirectional electromagnetic field in the vicinity of the alley at a position intermediate the ends of the alley.
Each animal to be identified wears a transponder that becomes energized when exposed to the electromagnetic field. When energized, each transponder transmits identifying data back to the antenna loop. A decoding circuit coupled with the antenna decodes the identification data and identifies the animal wearing the transponder.
Identification apparatuses such as the one described above are typically coupled with a sorting gate such as a cutter gate for sorting animals after they have been identified for special handling such as periodic medical treatment or the like. Conventional sorting gates include an elongated alley having a first end presenting an entrance and a second end presenting a main exit and a sort exit. An automatic gate is positioned in the second end of the alley for movement between a sorting position in which the gate blocks the main exit and opens the sort exit, and a non-sorting position in which the gate opens the main exit and closes the sort exit. When an animal to be sorted is detected by the identification apparatus, an electrical signal is produced that triggers a controller or valve to move the gate to the sorting position.
The identification apparatuses may also be coupled with dairy parlor entry gates for controlling entry into milking stalls and pens. Conventional dairy parlor gates are similar to the sorting gates described above except that they are typically placed near the entrance to milking stalls rather that adjacent a sorting area.
Prior art animal identification apparatuses suffer from several limitations that limit their utility. For example, since prior art animal identification systems typically have antennas that are mounted in flexible curtains, animals often push the antennas aside and escape from being identified.
Another problem with prior art animal identification systems is the difficulty in reading the transponder of the first animal in a string. The sorting gate or the parlor entry gate on conventional animal identification systems is usually positioned downstream of the antenna. This is a problem because the first animal in a sting may be past the antenna when the gate opens, therefore its transponder is not activated by the antennas.
Moving the sorting gate upstream of the antenna is not practical because the animals must be identified before they are sorted. Similarly, moving the entry gate upstream of the antennas is not desirable because it is preferred to position dairy parlor entry gates on the milking stall side of the antennas so that the gate can hold the last cow of the preceding string in position. For example, when the gate is in the closed position, the last cow is held between a stanchion and the entry gate to prevent her from moving out of position and the reach of the herdsman.
Rigid antennas for use in animal identification systems are known in the art. However, these prior art rigid antennas have been used only in support posts and the like and do not allow sorting of animals. These prior art rigid antennas also suffer from the above-described "first cow" problem.